The Willis Tower, completed in 1973 as the Sears Tower, was the world’s tallest building for 23 years and adopted its current name in 2009 as part of an agreement in which London-based insurance broker Willis Group Holdings agreed to lease a portion of the building and got naming rights at the same time.

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Chicago's tallest building could soon have a new owner.
The 110-story Willis Tower is for sale and already has a likely buyer, a source said late Tuesday.
Commercial real estate broker Eastdil Secured is handling the building’s sale, the source said.
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